Scripts can grow dated. Revivals can suffer in comparison to a successful film adaptation. But Westside Theatre’s Off Broadway redo of Cactus Flower — the 1965 Abe Burrows farce that became an acclaimed 1969 film starring Goldie Hawn, Walter Matthau, and Ingrid Bergman — has even bigger issues. It’s poorly staged, terribly miscast, and just plain difficult to sit through.

Burrow’s setup is intriguing enough: Middle-aged playboy dentist Julian (Maxwell Caulfield) has been carrying on a yearlong love affair with 21-year-old record-store clerk Toni (Jenni Barber), but keeps her at arm’s length by pretending to be married with children. When Toni tries to gas herself, Julian decides it’s time they settle down, but first he has to divorce his nonexistent wife. Enter Stephanie (Lois Robbins), Julian’s dedicated spinster nurse, who agrees to pose as his better half. Problem is that she also wants to be his better half.

Hilarity could ensue, but it doesn’t. Dialogue that should have the spitfire sizzle and screwball speed is delivered at a snail’s pace. By the time the punchlines are spoken, the setups are forgotten. Toni, as Oscar-winner Hawn played her, was sweet, quirky, energetic — and just self-centered enough that you knew she’d never be a real adversary to Stephanie. But as Barber depicts her, rocking back on her heals and pouting like a child, she’s simply cloying. Lines that could land as cute (Toni repeatedly says ”I fizzled it” in reference to her failed suicide attempt) just make her seem stupid. You’re supposed to think men fall for Toni’s little-girl beauty (she wears a pink nightie and bunny slippers) and wide-eyed innocence, but you’re left wondering why they like her at all.

Robbins’ Stephanie, on the other hand, is so heavily primped, tousled, and self-assured from the start that she’s hard to believe as a lovelorn spinster whom Julian overlooked for a decade. Yet the way Robbins tosses back her head and soaks every line with self-importance, you’d understand why he would want to. The play momentarily comes alive during an Act II dance sequence in which Caulfield shows off the rhythm that made him semi-famous in Grease 2. Yet, the energy dies as soon as Stephanie introduces a dance called ”the dentist,” which involves pinching the air in front of your mouth with your fingers (yeah, I didn’t get it either). It should be a declaration of her resentment towards Julian and her unwillingness to keep embarrassing herself to please him — yet the moment actually is embarrassing.

Anna Louizos’ single set — which, with a few adjustments, stands in for Toni’s small studio apartment, a record store, Julian’s office, and a cocktail bar — is so overdone with 1960s cool (wood-paneling, rock posters, pink candle holders, yellow glass) that it feels more Urban Outfitters trendy than period authentic. As a result, the racism and sexism occasionally spouted by the characters doesn’t come across as ”genuine to the time,” but jarring and uncomfortable — taking you right out of what’s supposed to be a frothy romantic comedy. This show goes down as easily as spoiled milk. D